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Asked by bobo to Iain, Jo, Leo, Mariam on 22 Jun 2010 in Categories: General.
Question: How do you know there are different galaxies when you can't even get out of Milky Way?
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Joanna Watson answered on 22 Jun 2010:
From your profile it sounds like you almost certainly know more about astronomy than I do! I think that we know about different galaxies from the light that they emit.
I saw a TV show recently where they showed a picture of the universe with little specs of light that had travelled so far that they were thought to have first been emitted really soon after the big bang. That’s pretty cool isn’t it!
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Iain Moal answered on 22 Jun 2010:
With telescopes.
Soon after the invention of photography in the 1800s, astronomers starting taking photos through their cameras. What they could do is leave the shutter of the camera open for a long time, to see if they could pick up things that were too faint to see with just the eye and a telescope. What they saw amazed them. They saw hundreds of thousands of dots. Today, telescopes are much more powerful and see billions of spots, many in great detail. We can see galaxies of all shapes and sizes, and these can be classified into different types.
You can even help scientists classify galaxies, on the galaxy zoo website: http://www.galaxyzoo.org/
It tells you exactly how to classify the galaxies into different types. So far, over 60 million galaxies have been classified, but they have so many images that there is still lots of work to do. Have a go!
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Mariam Orme answered on 22 Jun 2010:
Erm, that’s a great question, and I have no idea what the answer is!
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Leo Garcia answered on 22 Jun 2010:
We can see other galaxies in the nearby universe with enormous telescopes, like the Hubble telescopes. So, whilst we can’t (for the moment) even hope to travel out of the Milky Way, we can detect electromagnetic radiation from galaxies outside our own, and the amazing pictures look like this:
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